Many food products are dried for purposes of packaging, storage and longevity. For example, dehydrated beans remain stable for a significant time prior to use, as compared to their hydrated counterpart. In certain food processing operations such as frozen food entree packaging, however, the dehydrated beans must be re-hydrated. In some applications, re-hydration may be combined with cooking or blanching.
Most dry vegetable products consist of a skin and a starchy inner substrate. Re-hydration procedures reintroduce water into the inner substrate by passing through the skin. In such re-hydration processes the skin acts as a natural membrane surface, passing much more fluid through than it itself absorbs. The rate of absorption is proportionate to several variables among which are temperature and pressure to which the product is exposed. One example of bean re-hydration is simply soaking the beans in water.
Bean hydration by cold soaking can take up to 24 hours and, as a result, exacerbate product color loss and reduce quality.
Other re-hydration processes apply temperature and pressure to decrease re-hydration processing time. Processing at increased temperature and pressure create different problems. High temperature and pressure can create product damage or impair product quality.
Further, releasing pressure at a time when the temperature is above the boiling point of water for a new, lower pressure, causes the skin of beans to rupture. Slowly cooling the product can reduce the risk of damage. This, however, increases re-hydration time.
Both cold soaking and increased pressure and temperature re-hydration use batch processes. Batch process tend to be expensive, because of high labor costs and, for the latter process, energy costs. To control and eliminate product damage when processing at increased temperature and pressure, each batch must be cooled entirely before the internal pressure can be released. The batch process is energy inefficient, because a single vessel is both heated and cooled. Moreover, repeated heating and cooling cycles create stress on the pressure vessels, which shorten their useful life and create potential workplace hazards.
Others have attempted to solve these batch processes problems through continuous process apparatus. Most of these solutions merely provided multiple batch vessels, and do not deliver a true continuous process. These apparatuses retain the problems associated with batch processes. Other attempts at providing a true continuous process apparatus have proved impracticable, because the required equipment size lengths grow beyond practical manufacturing facility boundaries.
In summary, existing batch food processing systems are slow, labor intensive, inefficient, and subject the product to potential quality impairment. The food processing industry needs an apparatus which will decrease processing time, save energy, increase yields and insure product quality. The present invention provides a solution to that need.